The goals of this program are to study events in hepatitis B virus replication, to characterize molecular forms of hepatitis B virus in chronically infected human tissues, and to investigate mechanisms whereby the virus perpetuates the process of infection. Our basic premise is that HBV genetic elements and/or specific viral gene products cause pathophysiologic consequences of chronic infection, including the asymptomatic carrier state, chronic inflammatory liver disease, and hepatocyte transformation. Our specific aims will be to study molecular forms of HBV genomes accumulating in liver during persistent infection and investigate how these molecular forms and their accumulation might relate to (1) enhancement of viral integration into host genomes, (2). formation of free viral DNA with structural rearrangements, (3) rearrangement of viral and cellular sequences in the host genome, and (4) formation of defective or reduced amounts of HBV core protein during the transitional phase from replicative to non- replicative infection. Specific experiments will utilize modern molecular and cellular methods to examine valuable tissue samples from South African blacks who show an apparent defect in the virus replication and/or assembly/secretion pathway, as well as tissues from Greek patients with replicative vs. non-replicative infection. Specifically, we will use molecular hybridization, cloning, sequencing and immunological methods to characterize HBV molecules and viral proteins accumulating in .these tissues. By this approach, using modern molecular and cellular techniques, the candidate hopes to gain further understanding of the role of HBV and its integration into the hepatocyte genome in perpetuating chronic infection, which ultimately leads to one of its major sequelae, hepatocellular carcinoma.